On July 21, 1959, former U.S. First Lady Mamie Eisenhower smashed a champagne bottle against the massive hull of the NS Savannah before the newly built ship plunged into the Delaware River, carrying with it the lofty promise that shipping would forever be changed.
Instead of having a conventional diesel engine in her engine room, Savannah was powered by a nuclear reactor. Between 1962 and 1970, at a time when nuclear power was considered the future of energy, merchant ships transported goods and people around the world to demonstrate the peaceful uses of split atoms.
Today, only a few countries still operate nuclear-powered ships, and mostly for military use in aircraft carriers and submarines. For example, Russia continues to employ a small fleet of nuclear icebreakers on the so-called Northern Sea Route in the Arctic.
Cargo ships running on nuclear fuel, leave alone passenger ships, have all but disappeared. But some are convinced it’s time to bring them back.
shipping carbon emissions problem
Merchant ships carry approximately 80% of all goods traded internationally, making them indispensable to keeping the global economy running.
But the majority still run on bunker oil, a thick, tar-like fuel made from crude oil, and have smokestacks that spew toxic pollutants into their air. Collectively, they emit as much climate-changing CO2 as the entire country of Japan.
The International Maritime Organization, which is responsible for global shipping, wants the sector to achieve net zero emissions by around 2050.
But none of the technologies promoted to substantially curb greenhouse gas emissions – batteries, for example, or alternative fuels such as methanol and ammonia – are capable of achieving this goal on their own.
Making a case for nuclear-powered ships
As global efforts to reduce CO2 emissions intensify, the issue of nuclear power in shipping is receiving increasing attention.
The most obvious benefit, Jan Emblemsvaag, engineering professor and project lead at the Norwegian research consortium NuProShip, told DW is that nuclear-powered ships “will have no emissions.”
Inside the NS Savannah, in the 1960s, a so-called pressurized water reactor was using nuclear fission to heat water, which then produced steam to turn turbines and power the ship’s propellers and electrical generators.
Then and now, the advantage of using nuclear fuel is that large amounts of energy can be packed into a relatively small space, enabling ships to cross oceans for years without refueling.
“And that, of course, gives a tremendous range,” Emblesvag said.
For example, the NS Savannah can make 14 trips around the world on one fuel load, whereas current container ships typically running on oil don’t manage a single trip.
Sometimes, they also need to reduce speed to save fuel. In contrast, nuclear ships would not have refueling problems, so they could move faster and save money at the same time.
Who killed NS Savannah?
Ultimately, it was the business case behind NS Savannah that led to her demise in 1970. Built at a cost of $46 million (€39.6 million) – about $500 million in purchasing power parity today – the ship required large annual government subsidies to operate, about $2 million, which was not financially sustainable, especially during a period when oil was cheap.
In addition, the ship was hampered by its limited cargo capacity of only about 10,000 tons, the need for a specially trained crew, and limited access to ports around the world due to nuclear safety concerns.
Additionally, the ship’s design was expensive, with thick shielding around the reactor and extendable wings to keep the ship stable in stormy waters.
NS Savannah was officially retired in 1970, with its nuclear reactor decommissioned and defueled in 1971.
Subsequently, only three other nuclear cargo ships were built – Germany’s Otto Hahn, the Japanese Mutsu and the Russian Sevmorput. The first two were later converted to diesel ships, and Sevmorput is near retirement.
New reactor types for technological breakthrough?
Mark Tipping of Lloyd’s Register, the global shipping classification society, said the current discussion about a nuclear revival in shipping is driven primarily by technological advances in developing next-generation nuclear reactors.
“The technologies we are considering for the maritime sector today are very different from those implemented in the 1960s and ’70s,” he told DW.
Often referred to as “Generation IV” reactors, their biggest promise is that they will be safer than in the past. Pressurized water reactors (PWRs), the most common type of reactor today, rely on active intervention when things go wrong, meaning that, for example, additional pumps have to be kicked in.
“The new reactors will take that out of the equation,” Tipping said. “If something goes wrong, they’re fail-safe. They don’t need people to get it.”
The hope is that this will convince port authorities to allow nuclear ships to dock more readily.
Emblemsvåg’s Norwegian consortium – which includes the Norwegian University of Science and Technology and shipbuilder Verd – looked at 80 different new reactor designs, choosing three of which they consider the most promising for powering ships.
Apart from nuclear safety questions, he also looked at commercial aspects.
“We have already done some cost calculations for one of the reactor technologies we are working on. They indicate that the cost of the fuel will be about 40% cheaper than heavy fuel oil,” Emblemsvag said. He said the reactors selected are small and can be produced on a large scale, which will further reduce costs.
But none of the reactors tested by the consortium have actually been built yet, let alone established the production capacity to build them in large numbers.
When asked today about the potential of nuclear ships, some of the world’s largest shipping companies – MSC, CMA CGM and Maersk – did not even respond to DW’s request for comment.
Will nuclear powered ships remain only for sailors?
In June, the International Maritime Organization (IMO) agreed to update its rules governing civilian nuclear ships, which date back to 1981 and cover only PWR reactors.
Ricardo Batista, technical officer for maritime safety at the IMO, said the authority first wanted to understand the threats and safety requirements.
“And then from there, [we can] “Develop relevant mitigation measures that can be incorporated into the new code,” he told DW.
The IMO expects this process to take several years, with the operation of nuclear ships raising serious questions: How can we prevent nuclear fuel from leaking if a ship sinks? How can we prevent it from falling into the hands of terrorists? And what happens to nuclear waste?
In addition, classification societies, such as Lloyd’s Register in London or the US-based ABS that establish and enforce technical regulations, need to update their guidelines. And port authorities as well as ship insurers will have to revise their rules.
So sorting out all the legal aspects of nuclear-powered ships will probably take longer than building them. As Tipping and Emblemsvag hope, taking them to sea in the early 2030s seems ambitious.
Edited by: Uwe Hessler